Safety valve for wells

ABSTRACT

A safety valve to be lowered into a well and actuated from a location near the surface of the earth by a flexible line or the like extending downwardly into the well, and having a reversing mechanism acting to convert upward movement of the actuating line to downward movement of a valve opening part in the well, with the reversing mechanism including two pistons or other parts exposed to a common body of confined fluid in a relation causing downward displacement of one of the parts in response to upward movement of the other part.

United States Patent Boyadjieff et al.

[451 Jan. 21, 1975 [73] Assignee: Varco International, Inc., Los

Angeles, Calif.

22 Filed: Oct. 29, 1973 211 Appl. N01; 410,418

[52] US. Cl 166/224 A, 166/72, 251/63.6 [51] Int. Cl E2lb 43/12, E2lb33/03 [58] Field of Search 166/72, 73, 224, 274 A,

[56] References Cited UNITED STATES PATENTS 5/1933 Otis 166/72 7/1940Toney..... 8/1944 Erwin 166/72 3,078,923 2/1963 Tausch 166/224 S3,351,133 11/1967 Clark et al.... 166/72 3,411,585 11/1968 Page 166/733,675,718 7/1972 Kanady 166/224 S Primary Examiner-James A. LeppinkAttorney, Agent, or Firm-Wil1iam P. Green [57] ABSTRACT A safety valveto be lowered into a well and actuated from a location near the surfaceof the earth by a flexible line or the like extending downwardly intothe well, and having a reversing mechanism acting to convert upwardmovement of the actuating line to downward movement of a valve openingpart in the well, with the reversing mechanism including two pistons orother parts exposed to a common body of confined fluid in a relationcausing downward displacement of one of the parts in response to upwardmovement of the other part.

18 Claims, 7 Drawing Figures "n "Elli t PATENTED JANZ 1 I975 SNEU 10F 2SAFETY VALVE FOR WELLS CROSS REFERENCE TO RELATED APPLICATION Certainfeatures of the apparatus disclosed in the present application have beenshown and claimed in our prior copending application Ser. No 252,808filed May 12, 1972 on Remotely Operated Well Safety Valves, which was acontinuation in part of application Ser. No. 203,142 filed Nov. 30, 1971and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to improved wellsafety valves for closing off the flow of well fluid at a location deepwithin a well, and adapted for remotely controlled actuation and controlfrom the surface of the earth.

Our above identified prior copending application Ser. No. 252,808 showsa remotely controlled safety valve which is actuated from a locationnear the surface of the earth by actuation of a flexible line extendingdownwardly within the well to the location of the valve. The line orcable is preferably maintained under tension when the valve is open, sothat any release of that tensioned condition, either intentionally oraccidentally, will automatically close the valve and shut off furtherescape of well fluid therefrom. Thus, the valve will close if adverseconditions develop which in some way break the cable, or break thesupply of energy to an actuating unit at the surface of the earth whichmaintains the line in tension. This actuating unit may be a piston andcylinder mechanism located within an upper portion of the well and heldin a line-tensioning condition by the force of a pressurized controlfluid.

SUMMARY OF THE INVENTION The present invention provides a safety valveunit which can be controlled remotely in a manner similar to the valvesof my above discussed copending application, but in which the structureand functioning of the valve mechanism are different from, and forcertain situations or installations preferable to, the valves of thatprior application. One feature of particular importance to the presentinvention relates to the provision of a unique type of force reversingmechanism, which can be actuated by force applied to the mechanism in afirst vertical direction through the flexible line or other actuator,and which will function to reverse the direction of that force toproduce a valve operating force in the opposite vertical direction.Consequently, if a first of these forces is applied to the reversingmechanism by a flexible line of the above discussed type in an upwarddirection tensioning that line, the reversing mechanism can then applyto the valve or a valve operator a downward force for opening the valve,and holding it open until the tensioned condition of the flexible lineis released. The force reversal is effected by a fluid type system, inwhich a confined body of fluid is exposed to and acts against twodifferent movable parts, both of which may be considered as pistons, ina relation such that movement of one of the parts or pistons in a firstdirection acts through the fluid to cause movement of the other part inthe opposite direction. Desirably, both of these pistons are tubular toprovide within the interior of the pistons a relatively open verticalpassageway through which the production fluid of the well can flowupwardly without substantial restriction to the surface ofthc earth. aportion of one of these parts may actuate the safety valve proper from aclosed position of extension across the fluid passageway in the deviceto a laterally deflected open position. In that open position, a portionof the tubular piston element may extend vertically past the valveelement, in a manner protecting or shielding it from contact with anddeterioration by the upflowing stream of well fluid.

Another feature of the invention relates to a novel arrangement foractuating an equalizer valve, which functions to place the interior ofthe valve unit in communication with its exterior at a location abovethe main safety valve element proper just prior to opening of the mainvalve element, in order to eliminate or decrease the pressuredifferential across the main valve and thereby facilitate its openingmovement. More particularly, this equalizer valve controls the flow ofwell fluid through an aperture or apertures in the wall of the valveunit body, at a location above the main safety valve element, and isactuable to open condition by initial upward movement of the actuatingline. To assure opening of the equalizer valve before the mechanismattempts to open the main valve, a lost motion connection is providedwhich upon upward movement of the actuating line first opens theequalizer valve, and only after that valve has been opened commencesactuation of the mechanism which opens the main valve element. A springmay yieldingly resist this lost motion, and a second and opposed springmay resist relative motion of the parts in an opposite verticaldirection in a relation opening the equalizer valve during lowering ofthe tool into the well.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features andobjects of the invention will be better understood from the followingdetailed description of the typical embodiment illustrated in theaccompanying drawings, in which:

FIG. 1 shows somewhat diagramatically a well containing safety valveequipment constructed in accordance with the invention;

FIG. 2 is an enlarged vertical fragmentary section through variousportions of the apparatus of FIG. 1, showing the main safety valveelement in its open condition;

FIG. 3 is a view showing the lower portion of the FIG. 2 apparatus, butwith the safety valve in its closed condition;

FIG. 4 is an enlarged vertical section through the equalizer valvemechanism in its FIG. 2 condition;

FIG. 5 is a view similar to FIG. 4, but showing the equalizer valveclosed, as in FIG. 3;

FIG. 6 is an enlarged fragmentary vertical section taken in the area ofthe circle 66 of FIG. 3 and;

FIG. 7 is an enlarged vertical fragmentary section showing a portion ofthe main valve, in the region of the cricle 77 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows at 10 a wellcontaining a casing 11 within which a string of production tubing 12extends downwardly, in spaced relation to the casing. A conventionalwell head represented at 13 is connected to the upper end of the casing,and appropriately suspends the tubing string 12. Production fluid fromthe formation surrounding the well enters the lower end of the tubingstring at the production zone 14, and ultimately discharges from theupper end of tubing 12 into a storage tank 16 or appropriatedistribution line past a suitable control valve 116. The tubing 12 maybe formed in conventional manner of a series of tubing sectionsconnected together by threaded couplings 15. In lieu of the typicallyillustrated type of well drilled directly into the surface of the earth,it is contemplated that the present well safety apparatus may also beutilized in the drilling of underwater wells, as from a barge or shipfloating on the surface of a body of water, with the well casing and itscontents extending downwardly through the water to the ocean floor orthe like, and then into the earth at that location.

The safety valve unit proper is designated generally by the number 17 inFIG. 1, and is set in fixed position within the lower portion of tubingstring 12 by a landing and sealing unit represented at 18. Unit 18 maybe constructed integrally with valve unit 17, or may be a separatelyformed attached conventional landing and sealing unit as illustrated,rigidly connected to the upper end of the valve unit 17 by a threadedconnection 19 (FIG. 2). The safety valve is actuated and controlled byan elongated flexible line 20, preferably of the type commonly referredto as a wireline. This line or cable extends upwardly to the surface ofthe earth for control by a powered operating mechanism designatedgenerally at 21. The line 20 may be any conventional or known type offlexible cable or the like, including elements of this type formed ofeither a single wire or strand, or a number of wires or strandsinterwoven or wound together.

The landing and sealing unit 18 is typically and somewhatdiagramatically illustrated as of the same conventional key-type shownand described in our above identified copending application.Specifically, this unit 18 may include a tubular body member 22connected at its lower end to the upper end of body 23 of valve unit 17by the previously mentioned threaded connection 19, with an annular sealring 24 of rubber or other elastomeric material clamped betweenshoulders on elements 22 and 23 as seen in FIG. 2 for annular engagementwith the inner surface of tubing 12 to form a fluid tight seal therewithpreventing upward flow of fluid about the outside of elements 22 and 23at the location of seal 24. Disposed about body 22, the landing andsealing unit 18 includes a sleeve or mandrel 25 containing aperturesthrough which a number of circularly spaced locking keys or dogs 26project radially outwardly for interfitting reception within a matinglocating groove or plurality of grooves 27 formed in a coacting locatingor landing nipple 28 connected into tubing 12. As is conventional inthis type of device, keys 26 may be spring pressed radially outwardlyrelative to sleeve 25 for automatic reception within the groove orgrooves 27 when they reach the location of the groove, with the keysthen being locked in their outer holding positions in conventionalmanner by predetermined manipulation of body 22 from the surface of theearth. For example, the keys may be locked in their outer positions by arapid vertical jarring movement of body 22 serving to shear a connectionbetween the body and sleeve 25 and thereby move a looking or cammingportion of the body into a position behind or radially inwardly of thekeys. After being set by this type motion, the keys thereafterpositively lock sleeve 25 and body 22 against both upward and downwardmovement relative to section 28 of the tubing, to thereby positivelyretain the valve unit 17 in its FIG. 1 position in the lower portion ofthe tubing string. Any other type of conven tional landing equipment mayof course be substituted for the particular key-type device typicallyillustrated in FIG. 2, such as for example a type having slips designedto be forced outwardly against the tubing in frictional holdingrelation, or having lugs which are receivable between the ends ofsuccessive lengths of the tubing 12, or any other known or usable typeof apparatus controllable from the surface of the earth for holding thevalve unit 17 in a fixed vertical setting.

The actuating unit 21 located near the surface of the earth preferablytakes the form of an annular piston and cylinder mechanism, to which theupper end of the flexible line 20 is connectible, and through which acentral vertical passage 29 is formed for passing production fluidupwardly through the interior of this actuating unit. The cylinder 30 ofthe piston and cylinder mechanism 21 is an essentially tubular elementhaving a vertical cylindrical internal surface 31, and contains a piston32 which is movable upwardly and downwardly along the vertical axis 33of the well. The piston 32 has an upper enlarged diameter portion 34slidably received within and sealed by an O-ring 35 with respect to theinner cylindrical surface 31 of cylinder 30. An annular hydrauliccylinder chamber 36 is thus formed between the cylinder and piston,acting to force the piston upwardly relative to the cylinder in responseto the injection of pressure fluid into the chamber 36. The lower end ofchamber 36 is closed by provision of a reduced diameter portion 37 ofthe cylinder, having an internal surface 38 slidably engaging andreceiving the lower reduced diameter portion 39 of the piston, andsealed with respect thereto by an annular O-ring 40. Pressure fluid isintroduced into the lower end of cylinder chamber 36 through a smallfluid inlet line 41, connecting into the cylinder chamber at 42.

The upper end of piston 32 carriesa a spider 43, which supports atubular element 44 at a central location within the piston, so that theflexible line 20 may extend upwardly through this tubular portion 44 andbe attached to an upper enlarged head element 45 shaped to serve as afishing neck, for engagement with a fishing tool to pull the flexibleline upwardly if and when desired. Upward movement of the piston acts todisplace head element 44 and the connected flexible line upwardly, toopen the valve unit 17 and maintain the flexible line under tension.

The piston and cylinder mechanism 21 is preferably suspended in the wellfrom the well head 13, from which the usual main flow control valveassembly or Christmas Tree projects upwardly, the lower portion of thisvalve assembly being represented at 46 in FIG. 2. To suspend theactuating piston and cylinder mechanism from the well head, there isdesirably provded between elements 13 and 46 an adapter flange or ring47, suitably secured to the flanges of elements 13 and 46, andappropriately sealed with respect thereto as by rings represented at 48and 49. The upper end of cylinder 30 may be connected threadedly at 50to a short suspending tube 51, sealed with respect to the cylinder at 52and 53, and annularly sealed with respect to flange 47 at two verticallyspaced locations 54 and 55. One or more locking dogs 56 may bethreadedly connected into element 47 for projection into an annularexternal groove 57 formed in part 51, to suspend that part and theconnected piston and cylinder mechanism in the illustrated positionwithin the well. Actuating pressure fluid may be supplied to the pistonand cylinder mechanism through an inlet passage 58 communicating throughsmall passages 59 and 60 in elements 51 and 30 respectively with thepreviously mentioned line 41 extending downwardly to the lower end ofcylinder chamber 36. A fishing neck 61 may be connected onto the upperend of part 51, for engagement with an appropriate fishing tool toenable removal of the unit 21 upwardly from the well when desired. Theactuating pressure fluid is supplied to passage 58 from any appropriatesource represented diagramatically at 62 in FIG. 1, under the control ofa manually or automatically operable three way valve or other valverepresented at 63, for selectively either applying pressure to orreleasing pressure from the hydraulic cylinder chamber 36.

The novelty of the present invention is particularly concerned with thestructure of the safety valve unit 17 at the bottom of the well.Referring particularly to FIG. 2, the previously mentioned outer body 23of this valve unit may be a vertically elongated rigid tubular structure formed sectionally to include a first upper section 64 threadedlyconnected at 66 to a second section 65 in fluid tight annularly sealedrelation, with an annular bottom section 67 being threadedly connectedat 68 to the lower end of section 65. The main safety valve element is aflapper type valve 69, mounted pivotally at 70 for swinging movementbetween the closed horizontally extending position of FIGS. 3 and 5,disposed transversely of vertical axis 33 of the well and tool, and theopen position of FIG. 2, in which the valve 69 extends essentiallyvertically within an annular pocket or recess 71 formed in section 65 ofthe body 23. The pivotal axis 72 of valve 69 (see FIG. 7) is disposedhorizontally in the illustrated position of the tool, to lie in a planeextending transversely of vertical axis 33. In its closed position ofFIGS. 3 and 7, the circular valve disc 69 has its annular peripheralsurface 73 (FIG. 7) in annular sealing engagement with a seal ring 74carried by a radially inwardly projecting annular shoulder 75 formedwithin the interior of part 65, to positively close off all upward flowof production fluid through the valve unit and past element 69.

The valve element 69 is actuated to its open position by downwardmovement of a tubular part 76 whose upper portion 77 may function aspart of a reversing mechanism 78 acting to displace part 76 downwardlyin response to upward movement of flexible line and a connected element79 forming a second portion of the reversing mechanism. Part 79functions as an annular piston element, having a tubular straightcylindrical portion 80 slidably received within and engaging an internalcylindrical surface 81 formed in part 64 of body 23, and sealed withrespect thereto by an O-ring 82. Beneath the location of O-ring 82, part64 contains and enlarged diameter internal cylindrical surface 83,defining the outer wall of an annular vertically extending cylinderchamber 84 within which a body of pressure fluid is contained inconfined and hermetically sealed condition. At its lower end, theelement 79 has an annular radially outwardly projecting piston head 85.

Portion 77 or part 76 is shaped as a vertical tube functioning as asecond annular piston having parallel internal and external cylindricalsurfaces centered about axis 33. The outer surface of portion 77 of part76 slidably engages internal surface 83 of part 64, and is sealed withrespect thereto as by an O-ring 86. The

internal surface of portion 77 slidably contacts piston head 85 of theupper piston element 79, being sealed with respect thereto by anelastomeric ring 87 at its upper end. Portion 77 of part 76 maythreadedly carry an annular part 88, which may have a portion 89extending across the end of portion 77, and an axially ex tendingportion 90 projecting radially inwardly from and beyond the internalsurface of portion 77 of part 76, to define with the outer surface ofpiston element 79 an annular restricted passage 91, which providesrestricted communication between and has a radial width smaller than twoupper and lower annular fluid com partments 92 and 93 forming portionsof the previously discussed closed fluid chamber 84. This chamber andits two compartments 92 and 93 are filled with fluid in any suitablemanner, as by injection through one or more inlet passages 94 which,after injection of the fluid, may be closed and sealed by plugs 95 orotherwise. Desirably, the fluid within chamber 84 is a liquid, to renderthe actuation of the reversing mechanism as positive and controllable aspossible.

At the lower end of the piston portion 77 of part 76, this part has anannular portion 192 of increased radial thickness, defining a shoulder193 against which a compression spring 194 bears upwardly to yieldinglyurge part 76 upwardly toward the FIG. 3 closed valve condition thereof.Beneath the level of shoulder 93, part 76 has a reduced diameter tubularportion 195, which slidably contacts an internal cylindrical surface inshoulder portion 75 of body part 65, and which has an annular beveledlower end surface 96 engageable annularly with an upwardly facingsurface 97 formed on part 67 in the open position of valve 69, tothereby close off access of the production fluid within the interior ofpart 67 and 76 to the open valve 69. Thus, the valve is protectedagainst erosion by or other damage from contact with the movingproduction fluid. An opening 98 in the side wall of part 65 beneathshoulder 75 allows fluid flow into and out of the annular valvereceiving compartment 71, to avoid any tendency for restriction ofmovement of the parts by entrapment of fluid in this compartment.

At its upper end, the upper piston part 79 of the reversing mechanism 78is connected to flexible line 20 through an equalizing valve assembly 99and a landing weight 100. The landing weight 100 may be connected in ansuitable manner to the lower end of flexible line 20, and carry adownwardly projecting essentially rigid vertical rod 101 which isdetachably connectible to the upper end of equalizer valve assembly 99by a quick disconnect connection 102. As seen best in FIGS. 4 and 5,this connection 102 includes a part 103 disposed about the lower portionof rod 101 and forming a series of downwardly projecting circularlyspaced spring fingers 104 whose lower enlargements 105 are receivablewithin a socket recess 106 formed in the upper chuck portion 107 of body108 of the equalizer valve assembly 99. The part 104, rod 101 and weight100 are not lowered into the well until after the valve unit 17 andlanding unit 18 have been set therein. At that time, parts 100, 101, and103 are lowered into the well in a condition in which a lower cammingenlargement 109 carried by rod 101 is located downwardly beneath thelevel of enlargements 105 on spring fingers 104, as represented by thebroken lines 109' in FIG. 4. With the parts in this condition,enlargements 105 of the spring fingers 104 can move downwardly into thesocket recess 106, and then spring radially outwardly in that recess,and be retained in the FIG. 4 full line connecting position by upwardmovement of enlargement 107 rela tive to the fingers and to a positionbetween and blocking inward movement of the fingers. Thereafter, theconnection 102 secures the rod 101 to body 108, with sufficient strengthto withstand forces applied by the flexible line 20 in the FIG. 2 openposition of valve 69, and unless and until the cable 20 is forceablypulled upwardly with excessive force sufficient to shear a pin 110 whichinitially extends through and is carried by rod 101 in the position ofFIG. 4, but which upon exertion of an upper jarring force is sheared offto allow upward movement of rod 101 and its enlargement 109 from theFIG. 4 position to the FIG. position in which fingers 105 are free tomove radially inwardly for release from chuck 107.

The equalizer valve assembly includes a tubular slide valve element 111(FIGS. 4 and 5), which slidably engages the inner cylindrical surface112 of body part 64, and which in the normal closed position of FIG. 5to which it tends to return blocks fluid flow through one or moreapertures 113 formed in the side wall of part 64. When the valve isopen, these apertures 113 place the interior of body part 64 incommunication with its exterior, to apply the same pressure to the upperside of main valve element 64 as to its underside.

The body part 108 of equalizer valve assembly 101 is a verticallyextending tubular part, which rigidly carries sleeve valve element 111,as by provision of a series of circularly spaced radially extending webelements 114 connecting parts 108 and 111 but allowing upward flow ofproduction fluid between elements 114. Internally, part 108 has achamber 115 beneath the upper chuck recess 106, and within which twoupper and lower compression springs 116 and 117 are received above andbeneath an upper radial flange portion 118 carried at the upper end of arigid rod 119 which projects upwardly from and is rigidly attached tothe upper piston element 79 of the reversing mechanism 78. A seen inFIGS. 2 and 3, rod 119 may be connected to part 79 by providing thelatter with an upper reduced diameter portion 120 attached to the maintubular portion of part 79 by a web structure 121 containing circularlyspaced apertures 122 through which the production fluid can flowupwardly from the interior of part 79 to the space about rod 119.

To now describe a cycle of use of the disclosed apparatus, the firststep to be followed in placing the equipment in operation in a well isto lower valve unit 17 and landing and sealing unit 18 into the well andto a production zone location as represented in FIG. 1. At this time,the flexible line and all parts connected thereto above chuck 107 arenot attached to the units 17 and 18 which are lowered into the well. Anappropriate running tool lowers these units 17 and 18 and then actuatesthe unit 18 to lock itself and unit 17 in fixed position in the well.Thereafter, the flexible line 20 and connected parts are lowered intothe well, and fingers 105 are actuated to form a connection with chuck107 as seen in FIG. 4. The actuating mechanism 21 is appropriatelypositioned in the upper portion of the well, and the upper end offlexible line 20 is passed through part 44 and connected to upperelement 45 in an appropriate setting. Before application of pressure tothe actuating unit 21, the springs 116 and 117 retain element 108 andsleeve valve 111 in the FIG. 5 closed position of the equalizer valve,and spring 194 holds the part 76 in its FIG. 3 position in which themain valve 69 is also closed. When it is desired to open the safetyvalve to allow production of fluid from the well, control 5 fluid underpressure is applied to actuating unit 21 through passages 58, 59 and 60,and line 41, to force piston 32 upwardly to the FIG. 2 position, andthereby apply upward tensioning force to cable 20 moving that cableupwardly to its FIG. 2 position. The initial upward movement of thecable moves outer body 108 of the equalizer valve assembly upwardlyrelative to rod 109 and its head 118, against the tendency of spring117, and to a position in which sleeve valve element 111 is in itsbroken line position of FIG. 5 relative to part 64, to thereby open theequalizer or bleed passages 113. The strength of spring 117 is notsufficient to cause upward movement of rod 19 and its connected partsduring this initial upward movement of part 108. However, when slidevalve element 111 reaches its broken line position of FIG. 5, the spring117 is in its fully compressed condition and therefore transmits furtherupward movement of part 108 to rod 119, to correspondingly move piston79 upwardly relative to part 64, to thereby force liquid fromcompartment 93 through the restriction 91 and into the upper compartment92 of chamber 84. The increased amount of liquid in upper compartment 92forces the lower piston 77 downwardly in response to the upward movementof piston 79, to thereby displace the lower portion 195 of part 76downwardly to its FIG. 2 position opening main valve 69. The narrowdimension of restriction 91 limits the rate at which this motion of thepistons can occur, to prevent damage to the pistons and/or valve andother related mechanism by too rapid motion. While the well isproducing, the flexible line 20 is continuously maintained in thisupwardly displaced tensioned condition of FIG. 2 by the actuating unit21, to hold valve element 69 in its opened condition.

If any adverse condition develops during production which breaks cable20, as by an earthquake or the like, the tensional force exerted by thatcable is immediately released, and the main valve and equalizer valveare permitted to return to their normal closed positions, under theinfluence of springs 194 and 1 17. A coacting spring 123 associated withelement 169 may yieldingly urge that valve to its closed positionpivotally about its axis 72, to urge the valve closed upon upwardmovement of part 76. The pressure fluid itself will of course normallyassist this closure of valve 69, and maintain it positively closed byvirtue of the pressure differential at the opposite sides of the valvewhen the equalizer valve element 111 is closed.

The second spring 116 within the equalizer valve assembly 99 is providedfor permitting opening of the equalizer valve 1 11 during lowering ofthe units 17 and 18 into the well. During such lowering, the runningtool which installs these units in the well may displace part 108downwardly relative to part 119 against the tendency of upper spring 116, and downwardly beyond the FIG. 5 position of part 111, to move part111 out of blocking relation with respect to apertures 113 while theapparatus is being installed, and thereby allow fluid flow upwardly pastseal element 24 and prevent the fluid in the well from resistingdownward movement of the equipment.

While a certain specific embodiment of the present invention has beendisclosed as typical, the invention is of course not limited to thisparticular form, but rather is applicable broadly to all such variationsas fall within the scope of the appended claims.

We claim:

1. In well safety apparatus, including a valve unit to be lowered into awell and located therein, and a member extending upwardly toward thesurface of the earth for actuating said valve unit; the improvementcomprising formation of said valve unit to include means containing andenclosing a confined body of fluid, said means including a first elementconnectible to said member for actuation upwardly thereby and exposed toand acting against said confined body of fluid in a manner displacing aportion of said fluid in response to said upward movement of saidelement, and a second element exposed to said confined body of fluid andactuable downwardly by the pressure of the fluid upon said upwardmovement of said first element, said valve unit including also valvemeans operable by said downward movement of said second element.

2. The improvement in well safety apparatus as recited in claim 1, inwhich said two elements are pistons exposed to said body of fluid.

3. The improvement in well safety apparatus as recited in claim 1, inwhich said two elements are two concentric annular pistons movable inopposite vertical directions.

4. The improvement in well safety apparatus as recited in claim 1, inwhich said elements are two telescopically interfitting oppositelymovable piston elements exposed to said confined fluid, one of saidelements having a portion contacting said fluid which is thickerradially than an adjacent portion of said one element and which definesa restricted passage extending between and narrower than twocompartments containing said confined fluid and between which saidconfined fluid must flow upon relative movement of the two elements.

5. The improvement in well safety apparatus as recited in claim 1, inwhich said valve means include a valve element mounted to swingdownwardly and radially outwardly from a closed position blocking offthe flow of production fluid upwardly through the well to an openposition permitting such flow, said second element having a portionpositioned to engage said valve element and deflect it downwardly andoutwardly to said open position upon downward movement of said secondelement.

6. The improvement in well safety apparatus as recited in claim 1, inwhich said second element has a tubular lower portion through whichproduction fluid flows upwardly in the open position of said valvemeans, said valve means including a valve member mounted pivotally fordownward and outward swinging movement by downward movement of saidtubular portion of said second element and from a closed position to anopen position of reception radially outwardly of said tubular portion.

7. The improvement in well safety apparatus as recited in claim 1, inwhich said valve unit includes a body through which production fluidflows upwardly when said valve means are open, and equalizer valve meansoperable upon upward movement of said first element to place theexterior of said body in communication with its interior at a locationabove said first mentioned valve means.

8. In well safety apparatus including a body to be lowered into a welland located therein; a main valve member carried by said body andactuable between an open position passing production fluid upwardly intothe interior of the body and a closed position blocking off such fluidflow; an equalizer valve element movable be tween an open position forpassing fluid through a bleed passage formed in a side wall of said bodyand placing the exterior of the body in communication with its interiorat a location above said main valve member, and a closed position; anelongated member extending upwardly toward the surface of the earth andoperable by upward movement to open both said main valve element andsaid equalizer valve element; means for exerting upward force on saidelongated member from a location near the surface of the earth; and alost motion connection between said two valve elements acting to opensaid equalizer valve element upon initial upward movement of saidelongated member and to then open said main valve element upon furtherupward movement of the elongated member.

9. The improvement in well safety apparatus as recited in claim 8,including spring means yieldingly resisting movement of said equalizervalve element independently of said main valve element.

10. In well safety apparatus, including a valve unit to be lowered intoa well and located therein, and a member extending upwardly toward thesurface of the earth for actuating said valve unit; the improvementcomprising formation of said valve unit to include a first elementconnectible to said member for actuation upwardly thereby and exposed toand acting against a confined body of fluid in a manner displacing aportion of said fluid in response to said upward movement of saidelement, a second element exposed to said confined body of fluid andactuable downwardly by the pressure of the fluid upon said upwardmovement of said first element, and valve means operable by saiddownward movement of said second element, said valve unit including atubular vertically extending body defining a side wall of a chambercontaining said con fined fluid, one of said elements being an annularpiston having a tubular wall defining a second side wall of saidchamber.

11. In well safety apparatus, including a valve unit to be lowered intoa well and located therein, and a member extending upwardly toward thesurface of the earch for actuating said valve unit; the improvementcomprising formation of said valve unit to include a first elementconnectible to said member for actuation upwardly thereby and exposed toand acting against a confined body of fluid in a manner displacing aportion of said fluid in response to said upward movement of saidelement, a second element exposed to said confined body of fluid andactuable downwardly by the pressure of the fluid upon said upwardmovement of said first element, and valve means operable by saiddownward movement of said second element, said valve unit including atubular body defining a radially outer wall of a cylinder chambercontaining said confined fluid, one of said elements being tubular anddefining a radially inner wall of said cylinder chamber and having apiston head acting against the confined fluid at an end of the chamber.

12. In well safety apparatus, including a valve unit to be lowered intoa well and located therein, and a member extending upwardly toward thesurface of the earth for actuating said valve unit; the improvementcomprising formation of said valve unit to include a first elementconnectible to said member for actuation upwardly thereby and exposed toand acting against a confined body of fluid in a manner displacing aportion of said fluid in response to said upward movement of saidelement, a second element exposed to said confined body of fluid andactuable downwardly by the pressure of the fluid upon said upwardmovement of said first element, and valve means operable by saiddownward movement of said second element, said valve unit including avertically extending tubular body defining a radially outer wall of acylinder chamber containing said confined fluid, one of said elementsbeing a tubular part defining a radially inner wall of said chamberspaced radially from said outer wall and having a piston head actingagainst the confined liquid at an end of the chamber, the other of saidelements being an annular piston element extending telescopically intosaid chamber and between said inner and outer walls thereof and slidablyengaging said piston head in sealed relation.

13. In well safety apparatus, including a valve unit to be lowered intoa well and located therein, and a member extending upwardlytoward thesurface of the earth for actuating said valve unit; the improvementcomprising formation of said valve unit to include a first elementconnectible to said member for actuation upwardly thereby and exposed toand acting against a confined body of fluid in a manner displacing aportion of said fluid in response to said upward movement of saidelement, a second element exposed to said confined body of fluid andactuable downwardly by the pressure of the fluid upon said upwardmovement of said first element, and valve means operable by saiddownward movement of said second element, said valve unit including avertically extending tubular body defining a radially outer wall of acylinder chamber containing said confined fluid, one of said elementsbeing a tubular part defining a radially inner wall of said chamberspaced radially from said outer wall and having a piston head actingagainst the confined liquid at an end of the chamber, the other of saidelements being an annular piston element extending telescopically intosaid chamber and between said inner and outer walls thereof and slidablyengaging said piston head in sealed relation, said second element havinga portion within said chamber which is thicker than an adjacent portionof said element and defines with said radially inner wall of saidchamber a restriction between two compartments in the chambercontrolling the rate of displacement of said elements.

14. In well safety apparatus, including a valve unit to be lowered intoa well and located therein, and a mmeber extending upwardly toward thesurface of the earth for actuating said valve unit; the improvementcomprising formation of said valve unit to include a first elementconnectible to said member for actuation upwardly thereby and exposed toand acting against a confined body of fluid in a manner displacing aportion of said fluid in response to said upward movement of saidelement, a second element exposed to said confined body of fluid andactuable downwardly by the pressure of the fluid upon said upwardmovement of said first element, valve means operable by said downwardmovement of said second element, said valve unit including a tubularvertically extending body having a first smaller internal diameterportion and having therebeneath a larger internal diameter portiondefining an outer wall of a cylinder chamber containing said confinedfluid, said first element being an annular first piston having a tubularportion slidably received in and sealed with respect to said smallerinternal diameter portion and forming a radially inner wall of saidchamber and having a lower annular radially outwardly projecting pistonhead, said second element being an annular second piston projectingupwardly telescopically about said piston head and in engagementtherewith and telescopically within said chamber and in engagement withthe interior of said larger diameter portion of said body in a relationcausing downward movement of said second piston element relative to thebody in response to upward movement of said first piston elementrelative to the body, said second element having a downwardly projectingtubular portion movable downwardly therewith, a valve seat carried bysaid body and facing downwardly and past which said lower tubularportion of said second element is movable upon downward movement of thesecond element, said valve means including a flapper valve elementmounted to said body for swinging movement downwardly and outwardly bysaid lower tubular portion of said second element and from a closedposition of engagement with said seat to a downwardly projecting openposition of reception in the body at the outside of said lower tubularportion of said second element, and spring means yieldingly urging saidsecond element upwardly relative to said body.

15. The improvement in well safety apparatus as reicted in claim 14, inwhich said second element has a portion received within said chamber incontact with said confined fluid and projecting radially inwardlyfarther than an axially adjacent portion of said second element and intoclose proximity with said first element to define therewith a restrictedpassage narrower than two upper and lower compartments of said chamber,there being an upwardly facing annular seat surface carried by saidbody, and engageable annularly with the lower extremity of said lowertubular portion of said second element in the lowermost position.thereof to close off access of production fluid therepast to said valveelement.

16. In well safety apparatus including a body to be lowered into a welland located therein; a main valve member carried by said body andactuable between an open position passing production fluid upwardly intothe interior of the body and a closed position blocking off such fluidflow; an equalizer valve element movable vertically between twodifferent open positions in which it passes fluid through a bleedpassage formed in a side wall of said body and places the exterior ofthe body in communication with its interior at a location above saidmain valve member, and a vertically intermediate closed position; anelongated member extending upwardly toward the surface of the earth andoperable by vertical movement to open both said main valve element andsaid equalizer valve element; and a lost motion connection between saidtwo valve elements acting to open said equalizer valve element uponinitial vertical movement of said elongated member and to then open saidmain valve element upon further vertical movement of the elongatedmember, said lost motion connection being constructed to enable movementof said equalizer valve element both upwardly and downwardly from saidclosed position and to both of said open positions without openingmovement of said main valve element.

17. In well safety apparatus including a body to be lowered into a welland located therein, a main valve member carried by said body andactuable between an open position passing production fluid upwardly intothe interior of the body and a closed position blocking off such fluidflow, an equalizer valve element movable between an open position forpassing fluid through a bleed passage formed in a side wall of said bodyfor placing the exterior of the body in communication with its interiorat a location above said main valve member, and a closed position, anelongated member extending upwardly toward the surface of the earth andactuable vertically to open said main valve element and said equalizervalve element, and a lost motion connection between said two valveelements acting to open said equalizer valve element upon initialvertical movement of said elongated member and to then open said mainvalve element upon further vertical movement of the elongated member,said lost motion connection including a part operatively connected tosaid main valve element for opening the latter in response to upwardmovement of said part, a coacting part actuable by said elongated memberand operable by both upward and downward movement relative to the bodyto open said bleed passage, and two springs yieldingly resisting upwardand downward movement respectively of said coacting part relative tosaid first mentioned part.

18. The improvement in well safety apparatus as recited in claim 17, inwhich said first mentioned part is a hollow vertically elongated elementconnectiblc at its upper end to said elongated member and carryingexternally said equalizer valve element for movement upwardly anddownwardly therewith, said coacting part including a rod projectingupwardly into the interior of said first mentioned part and operativelyconnected to said main valve element and having an enlargement receivedvertically between said two springs.

1. In well safety apparatus, including a valve unit to be lowered into awell and located therein, and a member extending upwardly toward thesurface of the earth for actuating said valve unit; the improvementcomprising formation of said valve unit to include means containing andenclosing a confined body of fluid, said means including a first elementconnectible to said member for actuation upwardly thereby and exposed toand acting against said confined body of fluid in a manner displacing aportion of said fluid in response to said upward movement of saidelement, and a second element exposed to said confined body of fluid andactuable downwardly by the pressure of the fluid upon said upwardmovement of said first element, said valve unit including also valvemeans operable by said downward movement of said second element.
 2. Theimprovement in well safety apparatus as recited in claim 1, in whichsaid two elements are pistons exposed to said body of fluid.
 3. Theimprovement in well safety apparatus as recited in claim 1, in whichsaid two elements are two concentric annular pistons movable in oppositevertical directions.
 4. The improvement in well safety apparatus asrecited in claim 1, in which said elements are two telescopicallyinterfitting oppositely movable piston elements exposed to said confinedfluid, one of said elements having a portion contacting said fluid whichis thicker radially than an adjacent portion of said one element andwhich defines a restricted passage extending between and narrower thantwo compartments containing said confined fluid and between which saidconfined fluid must flow upon relative movement of the two elements. 5.The improvement in well safety apparatus as recited in claim 1, in whichsaid valve means include a valve element mounted to swing downwardly andradially outwardly from a closed position blocking off the flow ofproduction fluid upwardly through the well to an open positionpermitting such flow, said second element having a portion positioned toengage said valve element and deflect it downwardly and outwardly tosaid open position upon downward movement of said second element.
 6. Theimprovement in well safety apparatus as recited in claim 1, in whichsaid second element has a tubular lower portion through which productionfluid flows upwardly in the open position of said valve means, saidvalve means including a valve member mounted pivotally for downward andoutward swinging movement by downward movement of said tubular portionof said second element and from a closed position to an open position ofreception radially outwardly of said tubular portion.
 7. The improvementin well safety apparatus as recited in claim 1, in which said valve unitincludes a body through which production fluid flows upwardly when saidvalve means are open, and equalizer valve means operable upon upwardmovement of said first element to place the exterior of said body incommunication with its interior at a location above said first mentionedvalve means.
 8. In well safety apparatus including a body to be loweredinto a well and located therein; a main valve member carried by saidbody and actuable between an open position passing production fluidupwardly into the interior of the body and a closed position blockingoff such fluid flow; an equalizer valve element movable between an openposition for passing fluid through a bleed passage formed in a side wallof said body and placing the exterior of the body in communication withits interior at a location above said main valve member, and a closedposition; an elongated member extending upwardly toward the surface ofthe earth and operable by upward movement to open both said main valveelement and said equalizer valve element; means for exerting upwardforce on said elongated member from a location near the surface of theearth; and a lost motion connection between said two valve elementsacting to open said equalizer valve element upon initial upward movementof said elongated member and to then open said main valve element uponfurther upward movement of the elongated member.
 9. The improvement inwell safety apparatus as recited in claim 8, including spring meansyieldingly resisting movement of said equalizer valve elementindependently of said main valve element.
 10. In well safety apparatus,including a valve unit to be lowered into a well and located therein,and a member extending upwardly toward the surface of the earth foractuating said valve unit; the improvement comprising formation of saidvalve unit to include a first element connectible to said member foractuation upwardly thereby and exposed to and acting against a confinedbody of fluid in a manner displacing a portion of said fluid in responseto said upward movement of said element, a second element exposed tosaid confined body of fluid and actuable downwardly by the pressure ofthe fluid upon said upward movement of said first element, and valvemeans operable by said downward movement of said second element, saidvalve unit including a tubular vertically extending body defining a sidewall of a chamber containing said confined fluid, one of said elementsbeing an annular piston having a tubular wall defining a second sidewall of said chamber.
 11. In well safety apparatus, including a valveunit to be lowered into a well and located therein, and a memberextending upwardly toward the surface of the earch for actuating saidvalve unit; the improvement comprising formation of said valve unit toinclude a first element connectible to said member for actuationupwardly thereby and exposed to and acting against a confined body offluid in a manner displacing a portion of said fluid in response to saidupward movement of said element, a second element exposed to saidconfined body of fluid and actuable downwardly by the pressure of thefluid upon said upward movement of said first element, and valve meansoperable by said downward movement of said second element, said valveunit including a tubular body defining a radially outer wall of acylinder chamber containing said confined fluid, one of said elementsbeing tubular and defining a radially inner wall of said cylinderchamber and having a piston head acting against the confined fluid at anend of the chamber.
 12. In well safety apparatus, including a valve unitto be lowered into a well and located therein, and a member extendingupwardly toward the surface of the earth for actuating said valve unit;the improvement comprising forMation of said valve unit to include afirst element connectible to said member for actuation upwardly therebyand exposed to and acting against a confined body of fluid in a mannerdisplacing a portion of said fluid in response to said upward movementof said element, a second element exposed to said confined body of fluidand actuable downwardly by the pressure of the fluid upon said upwardmovement of said first element, and valve means operable by saiddownward movement of said second element, said valve unit including avertically extending tubular body defining a radially outer wall of acylinder chamber containing said confined fluid, one of said elementsbeing a tubular part defining a radially inner wall of said chamberspaced radially from said outer wall and having a piston head actingagainst the confined liquid at an end of the chamber, the other of saidelements being an annular piston element extending telescopically intosaid chamber and between said inner and outer walls thereof and slidablyengaging said piston head in sealed relation.
 13. In well safetyapparatus, including a valve unit to be lowered into a well and locatedtherein, and a member extending upwardly toward the surface of the earthfor actuating said valve unit; the improvement comprising formation ofsaid valve unit to include a first element connectible to said memberfor actuation upwardly thereby and exposed to and acting against aconfined body of fluid in a manner displacing a portion of said fluid inresponse to said upward movement of said element, a second elementexposed to said confined body of fluid and actuable downwardly by thepressure of the fluid upon said upward movement of said first element,and valve means operable by said downward movement of said secondelement, said valve unit including a vertically extending tubular bodydefining a radially outer wall of a cylinder chamber containing saidconfined fluid, one of said elements being a tubular part defining aradially inner wall of said chamber spaced radially from said outer walland having a piston head acting against the confined liquid at an end ofthe chamber, the other of said elements being an annular piston elementextending telescopically into said chamber and between said inner andouter walls thereof and slidably engaging said piston head in sealedrelation, said second element having a portion within said chamber whichis thicker than an adjacent portion of said element and defines withsaid radially inner wall of said chamber a restriction between twocompartments in the chamber controlling the rate of displacement of saidelements.
 14. In well safety apparatus, including a valve unit to belowered into a well and located therein, and a mmeber extending upwardlytoward the surface of the earth for actuating said valve unit; theimprovement comprising formation of said valve unit to include a firstelement connectible to said member for actuation upwardly thereby andexposed to and acting against a confined body of fluid in a mannerdisplacing a portion of said fluid in response to said upward movementof said element, a second element exposed to said confined body of fluidand actuable downwardly by the pressure of the fluid upon said upwardmovement of said first element, valve means operable by said downwardmovement of said second element, said valve unit including a tubularvertically extending body having a first smaller internal diameterportion and having therebeneath a larger internal diameter portiondefining an outer wall of a cylinder chamber containing said confinedfluid, said first element being an annular first piston having a tubularportion slidably received in and sealed with respect to said smallerinternal diameter portion and forming a radially inner wall of saidchamber and having a lower annular radially outwardly projecting pistonhead, said second element being an annular second piston projectingupwardly telescopically about said piston head and in engagementtherewith and telescopicAlly within said chamber and in engagement withthe interior of said larger diameter portion of said body in a relationcausing downward movement of said second piston element relative to thebody in response to upward movement of said first piston elementrelative to the body, said second element having a downwardly projectingtubular portion movable downwardly therewith, a valve seat carried bysaid body and facing downwardly and past which said lower tubularportion of said second element is movable upon downward movement of thesecond element, said valve means including a flapper valve elementmounted to said body for swinging movement downwardly and outwardly bysaid lower tubular portion of said second element and from a closedposition of engagement with said seat to a downwardly projecting openposition of reception in the body at the outside of said lower tubularportion of said second element, and spring means yieldingly urging saidsecond element upwardly relative to said body.
 15. The improvement inwell safety apparatus as reicted in claim 14, in which said secondelement has a portion received within said chamber in contact with saidconfined fluid and projecting radially inwardly farther than an axiallyadjacent portion of said second element and into close proximity withsaid first element to define therewith a restricted passage narrowerthan two upper and lower compartments of said chamber, there being anupwardly facing annular seat surface carried by said body, andengageable annularly with the lower extremity of said lower tubularportion of said second element in the lowermost position. thereof toclose off access of production fluid therepast to said valve element.16. In well safety apparatus including a body to be lowered into a welland located therein; a main valve member carried by said body andactuable between an open position passing production fluid upwardly intothe interior of the body and a closed position blocking off such fluidflow; an equalizer valve element movable vertically between twodifferent open positions in which it passes fluid through a bleedpassage formed in a side wall of said body and places the exterior ofthe body in communication with its interior at a location above saidmain valve member, and a vertically intermediate closed position; anelongated member extending upwardly toward the surface of the earth andoperable by vertical movement to open both said main valve element andsaid equalizer valve element; and a lost motion connection between saidtwo valve elements acting to open said equalizer valve element uponinitial vertical movement of said elongated member and to then open saidmain valve element upon further vertical movement of the elongatedmember, said lost motion connection being constructed to enable movementof said equalizer valve element both upwardly and downwardly from saidclosed position and to both of said open positions without openingmovement of said main valve element.
 17. In well safety apparatusincluding a body to be lowered into a well and located therein, a mainvalve member carried by said body and actuable between an open positionpassing production fluid upwardly into the interior of the body and aclosed position blocking off such fluid flow, an equalizer valve elementmovable between an open position for passing fluid through a bleedpassage formed in a side wall of said body for placing the exterior ofthe body in communication with its interior at a location above saidmain valve member, and a closed position, an elongated member extendingupwardly toward the surface of the earth and actuable vertically to opensaid main valve element and said equalizer valve element, and a lostmotion connection between said two valve elements acting to open saidequalizer valve element upon initial vertical movement of said elongatedmember and to then open said main valve element upon further verticalmovement of the elongated member, said lost motion connection includinga part operatively connected to said main valve element for opening thelatter in response to upward movement of said part, a coacting partactuable by said elongated member and operable by both upward anddownward movement relative to the body to open said bleed passage, andtwo springs yieldingly resisting upward and downward movementrespectively of said coacting part relative to said first mentionedpart.
 18. The improvement in well safety apparatus as recited in claim17, in which said first mentioned part is a hollow vertically elongatedelement connectible at its upper end to said elongated member andcarrying externally said equalizer valve element for movement upwardlyand downwardly therewith, said coacting part including a rod projectingupwardly into the interior of said first mentioned part and operativelyconnected to said main valve element and having an enlargement receivedvertically between said two springs.